September 19, 2020

Why Practical Ventilation Matters

Continuous air sanitization isn’t a new concept. After all, to improve indoor air quality we install filters in our central cooling and heating systems and add potted plants to increase oxygen output in our homes and offices. But actually, sanitizing the air requires a strict standard. Terms like air changes per hour or cubic feet per minute are standard industry terms, but what do they mean? Do they matter?

Particles, whether they’re infected aerosolized droplets or pet dander, linger in the air. They travel much farther and live longer than you expect. If the air isn’t filtered, hazardous particles can be inhaled into someone’s respiratory tract, which causes illness. When it comes to volatile organic compounds–the kind emitted by ordinary cleaners, paint, and furniture–these build up in the body and can produce long-term issues including cancer and heart disease.

Air filtration, which involves both increasing ventilation and removing particulate matter from the air, is a broad term. It encompasses residential and commercial HVAC systems, consumer-grade air purifiers, and industrial air purification systems that can filter massive amounts of air quickly.

Making the right filtration choices, though, requires wading through industry terms and marketing jargon that might not be clear. For instance, how many air changes per hour do you need? What does CFM mean, and how do these features affect your purchasing decision? What’s the difference between ‘normal’ air purification and ‘medical-grade’ air purification? Should you be measuring square footage or cubic feet?

What Are Some Common Air Purification Terms?

Acceptable Air Exchange Rate (AAER)

The acceptable air exchange rate is the number of times per hour the air needs to be changed to achieve an acceptable level of risk based on environmental risk factors. This number is often dictated by industry-specific guidelines or regulations.

Air Changes Per Hour (ACH)

Air changes per hour can be represented by the acronym ACH. Air changes per hour is a peak standard in ventilation design and refer to the number of times the total volume of air in a room or building is completely changed in one hour. In hazardous environments, there are government-mandated air safety standards that must be met. In construction zones, for example, the accepted standard air changes per hour are six, or once every 10 minutes. In a hospital, the minimally acceptable standard is 12 or every 5 minutes–the same number of changes Omni CleanAir’s machines provide in an appropriately sized everyday workspace.

Cubic Feet Per Minute (CFM)

This acronym stands for cubic feet per minute, which is a method of airflow velocity measurement. Cubic feet is calculated by measuring the volume of air that can fit into one room. Measure height, length, and width–then multiply these numbers together. The result is the room’s volume. For instance, a box-shaped room with 100 feet x 50 feet x 20 feet will be 100,000 cubic feet. Angled ceiling and odd additions will complicate this math, but it can still be done. To find the CFM rate required for a given indoor space, take the total air volume, and divide it by the AAER (acceptable air exchange rate).

Medical-grade air purification

There are different standards for air changes per hour for specific industries. For instance, in the construction industry with toxic material like asbestos, the average air changes per hour are six. To calculate how many air changes per hour will occur, you’ll need to divide the room’s total volume by the CFM. Since Omni CleanAir’s machines are used in nuclear remediation projects and infectious disease/pandemic response, our machines are designed to achieve 12 air changes per hour when placed in typical everyday workspaces. The medical-grade standard ranges from 12-15 air changes per hour, which ensures the greatest degree of risk reduction possible.

Clean Air Delivery Metrics

When it comes to the clean air delivery rate for your workspace, you’ll need to calculate the cubic volume to determine the clean air delivery rate, which equals the number of air changes per hour.

The first step is to determine the amount of air in the area. In most situations, people will immediately start with the building’s square footage. It’s easy to measure, and your landlord already knows the answer. However, when it comes to air filtration, square footage is irrelevant. What matters is the total amount of air filling up your building. How much air can fit into the contained space?

That’s why cubic feet is an accurate measurement. To get this number, multiply the length by width by height. Picture water filling up a box–when you multiply those numbers together, you’ll know how many cubic feet of water is in that box. The same is true for how much air can ‘fit’ in a building. Once you know the volume of air contained by your building, you’ll know the cubic feet.

How many cubic feet per minute can the Omni CleanAir Professional Series machine process? The OCA1200 processes 1,200 cubic feet per minute. If the space it’s placed in is 6,000 cubic feet, divide the space’s cubic feet by the cubic feet per minute, and the resulting number is 5. This means the OCA1200 can filter and sanitize the entire volume of air in that space in 5 minutes.

How many air changes per hour are you looking for? Depending on your industry and the risk level you accept, the number varies. A minimum effective air change in the construction industry, for example, is 6 air changes per hour. To achieve a hospital-grade number of air changes, the number ranges from 12-15. The clean air delivery rate of a machine is dictated by how long it takes to conduct one complete air change.

For instance, an air change every five minutes equals 12 air changes per hour. With such a high clean air delivery rate, the complete volume of air in a room is continuously and rapidly being filtered and sanitized. If someone coughs into the room, the longest that those potentially infected aerosolized droplets will be suspended in the air is five minutes. That’s the standard our Omni CleanAir Professional Series machines provide.